I learned from my book that it was nothing but ten years of hard work that ______ his success in business.

1. A.
   led to
2. B.
   looked up
3. C.
   referred to
4. D.
   got through

I learned from my book that it was nothing but ten years of hard work that ______ his success in business.

   A. led to           B. looked up         C. referred to        D. got through

I learned from my book that it was nothing but ten years of hard work that ______ his success in business.

　 A. led to　　　　　 B. looked up　　　　 C. referred to　　　 D. got through

I learned from my book that it was nothing but ten years of hard work that ______ his success in business.